function [y]=F26(xx,m)
    if (nargin == 1)
        m = 10;
    end
    d = length(xx);
    sum = 0;
    for ii = 1:d
        xi = xx(ii);
        new = sin(xi) * (sin(ii*xi^2/pi))^(2*m);
        sum  = sum + new;
    end
    y = -sum;
end
%% ddd

x1=0:0.01:pi;
